When people worry about air pollution, they’re normally concerned about the impact it’s having on their lungs, and their children’s.

But what about their brains?

Last year, independent journalist and Ph.D. candidate in Clinical Neuropsychology at Duke University, Aaron Reuben, wrote an eye-opening exposé on the growing body of evidence that implicates air pollution as a major cause of Alzheimer’s and Parkinson’s. In the article, he discussed how small pollution particles — created primarily through fossil fuel combustion — can enter the brain through the nasal nerve and wreak havoc in multiple ways.

Sometimes pollution particles have heavy metal neurotoxins attached to them, which can kill neurons directly. But even when those particles don’t do immediate harm, they can cause damage by triggering an unquenchable immune response in the brain. This appears to result in a buildup of amyloid-beta plaques that are typically seen in people who are in a pre-Alzheimer’s or pre-dementia state.

That’s disturbing in its own right, but even more so when you consider the effect pollution can have on children.

“When you talk to people about amyloid-beta, they think dementia — they don’t think children,” Reuben said. “Well, children in at least one air-polluted city have been found with amyloid-beta plaques in their brain. They also have other kinds of brain damage from air pollution, including damaged vasculature, and leaky blood-brain barriers.”

In older populations, this effect accelerates aging and increases the risk of dementia-related diseases. But in places where researchers are able to measure kids’ exposure to air pollution and control for other external factors, what they found was alarming, Reuben said. Children exposed to higher rates of air pollution had an increased risk of developmental disorders like autism and ADHD. Of neurobehavioral problems. Of lower IQ.

It should be noted this is correlation, not causation, but it’s becoming clearer that air pollution is having a negative impact on our most vulnerable populations.

So what can we do?

One easy step is to use the circulate button more frequently when you’re driving in traffic or are able to smell the pollution. That alone can substantially reduce your exposure to air pollution.

On a larger scale, Reuben said one relatively low-cost solution would be implementing smarter land-use and urban planning to ensure that schools and nursing homes are built far away from busy roads. He also recommended more places follow in the footsteps of states like New York and Utah and enact ordinances to cut down on unnecessary engine idling.

However, these measures only address the problem by attempting to reduce exposure. To truly fix this issue, we need to clean up the sources of the pollution. And at the top of that list is addressing the “largest single source of air pollution” — transportation.

As mentioned above, the particle pollution that damages the brains of children and the elderly is made worse when fuel is combusted inefficiently — as in diesel vehicles, when idling, and when it’s cold. In a perfect world, zero-emission vehicles running cleanly generated electricity or hydrogen would be best, but right now electric and hydrogen vehicles still make up less than one-quarter of one percent of vehicles on the road and a significant plurality of electricity worldwide is generated by coal. However, a solution we could implement in the near future are high-octane fuels that allow for more efficient combustion, and more vehicles that have engines equipped to do exactly that. We already have the infrastructure in place to support these steps, and using a fuel that combusts more efficiently could reduce the amount of damaging particles that get spewed into the air we breathe every time we mash that gas pedal.

The sooner we get going on any and all of the above, the better. We can’t afford to wait.